Just a word of caution. There is I believe a size limit associated with the .SD files in particular the shared.sd which leads to a memory leakage.

I was being lazy and using the same TGA at 512*512 for both shared and strat as an extra file. However I noticed a corruption and after playing around narrowed it down to the shared.sd. I resolved it by using a much smaller file for the extra shared one and now it seems OK. Basically the SD file at 120,818 memory size was corrupting and a new one at 91,006 seems to be OK (sizes are read from the log file in trace).